The Machanism Of Alleviation Of Cancer Cachexia In MMP12 Konckout Mice

Objective and Background:In recent years,colorectal cancer（CRC）is a malignant gastrointestinal cancer,and among which some advanced patients will develop cancer cachexia（CAC）.CRC has increasing morbidity and mortality in the year by year,which threatens human health.CAC is a syndrome characterized by an ongoing loss of weight and skeletal muscle mass（with or without loss of fat mass）,which has seriously negative effect on the quality of survival of cancer patients and clinical chemotherapy drugs can not significantly improve its symptoms.Apc^Min/+mice are predisposed to spontaneous tumours,providing a good animal model for studying CAC.We unexpectedly found that knocking out MMP12 increase the body weight in Apc^Min/+mice.MMP12 is an endoprotease,which is mainly secreted by various inflammatory cells such as macrophages and monocytes.It has been reported that MMP12 can degrade insulin.Knockout MMP12 mice led to fat expansion under high-fat diet.Here,we intend to explore the effect of MMP12 knockout on the body weight in Apc^Min/+mice,and further explore its mechanism.Methods:We first obtain the Apc^Min/+;MMP12^-/-mice by crossing Apc^Min/+mice（an intestinal adenoma model of mice）with MMP12 knockout(MMP12^-/-)mice,using C57（WT）,MMP12^-/-,Apc^Min/+and Apc^Min/+;MMP12^-/-four group mice.The hematoxylin-eosin（H&E）stain was used to assess histological morphology.Immunohistochemistry and immunofluorescence staining were used to confirm the source and expression level of MMP12.Furthermore,enzyme-linked immunosorbent assay,protein arrays and real-time fluorescence quantitative PCR were used to verify whether the tumor causes IL-6 changes.The cell experiments and western blot were used to detect the expression level of MMP12 in macrophages,and to verify the regulatory relationship between IL-6 and MMP12.Quantitative fluorescence intensity and electrospray ionization mass spectrometry to confirm whether MMP12 could degrade insulin and insulin-like growth factor 1.Glucose tolerance test and insulin tolerance test were also performed to determine whether MMP12 caused abnormal glycolipid metabolism in Apc^Min/+mice.Finally,we use MMP12 inhibitors to explore whether inhibiting MMP12 wound affects the body weight of Apc^Min/+mice.Results:1.Apc^Min/+;MMP12^-/-mice genotype identification.2.Knockout of MMP12 causes weight gain in Apc^Min/+mice.3.Knockout of MMP12 expands the cross-sectional area of muscle fibers in Apc^Min/+mice.4.MMP12 is upregulated in muscle tissues and peritoneal macrophages of Apc^Min/+mice.5.Tumor cells can release IL-6.6.Tumor cells and IL-6 up-regulate MMP12 levels in macrophages.7.MMP12 can degrade insulin and insulin-like growth factor 1.8.MMP12 knockout mice affects glycolipid metabolism in Apc^Min/+mice.Conclusion:1.MMP12 knockout increase the body weight of Apc^Min/+mice.2.IL-6 released by tumor cells may recruit and activate macrophages, thereby up-regulating MMP12 expression.3.MMP12 can degrade insulin and insulin-like growth factor 1.MMP12 knockout affects glycolipid metabolism in Apc^Min/+mice.